Space scientists are holding their breath as a robot lab rides a comet toward the sun.

The lab, called Philae, landed on Comet 67P last November, and its mother ship, Rosetta has been orbiting nearby. Scientists hope the mission will help them discover more about the origins of the universe.

Thursday comet 67 will make its closest approach to the sun, coming within 186 million kilometers of the blazing star. Solar heat has been heating up the comet's surface for weeks, blasting off particles of gas and dust.

Sensors on Philae and Rosetta are to analyze the particles for rare molecules, particularly ones that may have been hidden beneath the comet's usually icy crust.

Because of the distances involved scientists may have to wait weeks or even months for the data to be beamed back to Earth.

The Rosetta mission was launched March 2, 2004 by the European Space Agency from its base in French Guyana. It arrived at the comet in August 2014.

When the robot lab landed, it bounced into a ditch where it was in shadow and not able to recharge its batteries. It was able to send data before going into standby mode.

As the comet neared the sun the lab's batteries recharged and in June it sent a two-minute message. But since July 9 Philae has been silent.

As Comet 67P leaves its close encounter with the sun, Rosetta will try to re-establish communications with the lab. Ground teams will be keeping their fingers crossed.